How to do URL decoding in Java

Question

In Java  I want to convert this   https 3A 2F 2Fmywebsite 2Fdocs 2Fenglish 2Fsite 2Fmybook do 3Frequest type   To this   https   mywebsite docs english site mybook do amp request type   This is what I have so far   class StringUTF        public static void main String   args                 try              String url                    https 3A 2F 2Fmywebsite 2Fdocs 2Fenglish 2Fsite 2Fmybook do                     3Frequest type 3D 26type 3Dprivate                System out println url  Hello World ------- gt                     new String url getBytes  UTF-8    ASCII                       catch Exception E                       But it doesn t work right   What are these  3A and  2F formats called and how do I convert them

User · Answer

The string you ve got is in application x-www-form-urlencoded encoding   Use URLDecoder to convert it to Java String   URLDecoder decode  url   UTF-8

User · Answer

import java io UnsupportedEncodingException  import java net URISyntaxException   public class URLDecoding         String decoded            public String decodeMethod String url  throws UnsupportedEncodingException               decoded   java net URLDecoder decode url   UTF-8             return  decoded     You should use java net URI to do this  as the URLDecoder class does x-www-form-urlencoded decoding which is wrong  despite the name  it s for form data               public String getPathMethod String url  throws URISyntaxException                decoded   new java net URI url  getPath              return  decoded              public static void main String   args  throws UnsupportedEncodingException  URISyntaxException                System out println   Here is your Decoded url with decode method      new URLDecoding   decodeMethod  https 3A 2F 2Fmywebsite 2Fdocs 2Fenglish 2Fsite 2Fmybook do 3Frequest type              System out println  Here is your Decoded url with getPath method      new URLDecoding   getPathMethod  https 3A 2F 2Fmywebsite 2Fdocs 2Fenglish 2Fsite 2Fmybook do 3Frequest                   You can select your method wisely

User · Answer

Using java net URI class   public String getDecodedURL String encodedUrl        try           URI uri   new URI encodedUrl           return uri getScheme           uri getSchemeSpecificPart          catch  Exception e            return               Please note that exception handling can be better  but it s not much relevant for this example

User · Answer

try           String result   URLDecoder decode urlString   UTF-8          catch  UnsupportedEncodingException e               TODO Auto-generated catch block         e printStackTrace

User · Answer

This has been answered before  although this question was first         You should use java net URI to do this  as the URLDecoder class does x-www-form-urlencoded decoding which is wrong  despite the name  it s for form data      As URL class documentation states      The recommended way to manage the encoding and decoding of URLs is to   use URI  and to convert between these two classes using toURI   and   URI toURL         The URLEncoder and URLDecoder classes can also be used  but only for   HTML form encoding  which is not the same as the encoding scheme   defined in RFC2396    Basically   String url    https 3A 2F 2Fmywebsite 2Fdocs 2Fenglish 2Fsite 2Fmybook do 3Frequest type   System out println new java net URI url  getPath       will give you   https   mywebsite docs english site mybook do request type

User · Answer

public String decodeString String URL             String urlString         try           urlString   URLDecoder decode URL  UTF-8              catch  UnsupportedEncodingException e                   TODO Auto-generated catch block                     return urlString

User · Answer

I use apache commons  String decodedUrl   new URLCodec   decode url     The default charset is UTF-8

User · Answer

This does not have anything to do with character encodings such as UTF-8 or ASCII  The string you have there is URL encoded  This kind of encoding is something entirely different than character encoding   Try something like this   try       String result   java net URLDecoder decode url  StandardCharsets UTF 8 name       catch  UnsupportedEncodingException e           not going to happen - value came from JDK s own StandardCharsets     Java 10 added direct support for Charset to the API  meaning there s no need to catch UnsupportedEncodingException   String result   java net URLDecoder decode url  StandardCharsets UTF 8     Note that a character encoding  such as UTF-8 or ASCII  is what determines the mapping of characters to raw bytes  For a good intro to character encodings  see this article

User · Answer

3A and  2F are URL encoded characters  Use this java code to convert them back into   and    String decoded   java net URLDecoder decode url   UTF-8

[java] How to do URL decoding in Java?

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